Pump



May 22, 1951 K. R. HERMAN HAL 2,553,655

PUMP

Filed March 14, 1946 2 Sheets-Sheet 1 Z: z- E Z l I I I4 '6 ils a n V /1A Mia-w nl was Hr ron/vw May 22 1951 K. R. HERMAN erAL 2,553,655

PUMP Filedmarch l14, 194e 2 sheets sheet g 5'7- TURA/Er Patented May 22,1951 PUMP Kenneth R. Herman, Franklin, and Ralph L. Tweedale,Birmingham, Mich., assgnors to Vickers Incorporated, Detroit, Mich., acorporation of Michigan Application March 14, 1946, Serial No. 654,314

This invention relates to power transmissions, particularly to those ofthe type comprising two or more fluid pressure energy translatingdevices, one of which may function as a pump and another as a fluidmotor.

The invention is more particularly concerned with a iiuid pressureenergy translating device of the multi-piston and cylinder types havingmechanically operated positively timed valving for controlling thedistribution of iiuid to and from the cylinders. Devices of thischaracterv are widely used in systems operating .at very high pressures4and frequently operate at very high speed. One disadvantage frequentlyencountered with units of this type is the production of considerablenoiseand a large part of this noise has been found to be generated asfluid pressure shock originating from improper timing of the admissionand release of pressure fluid to each cylinder.

Where the device is of the type using a rotating cylinder block havingindividual ports which cooperate with a stationary valve member havingmain inlet and outlet ports. thev valve timing is not capable ofadjustment after the device has been assembled since it is determined bythe length of the portsy in the valve member.

Many attempts have been made to improvethe action of this type of valvemechanism so as to make it noise free under all the various operatingconditions encountered, but these attempts have heretofore not beenentirely successful. y

It is an object of the present invention to provide an improved uidpressure energy translating device which retains, the advantages of thepositive mechanically operated valving, and yet which is capable ofoperating silently throughout a greater range of speed, pressure, andpiston stroke.

A further object is to provide. in a device of this character, a valvingstructure in which the normal mechanicalvalving has a lengthened cutoIfadacent dead-center piston position which blocks each cylinder in turnduring, a substantial part of the piston stroke, and to provide inaddition auxiliary valving means utilizing check valves for determiningthe exact time of opening of each cylinder to the high pressure or lowpressure port of the device or to both. In this way the advantages ofmechanically operated valving such as their usual large open iiowpassages are retained without their drawback of noisy operation.,Likewise. the` advantages of quiet operation obtainable when, checkvalves are. utilized and, because the 'check valve can be made small 6Claims. (Cl. 10S-162) and light, no diiculty is experienced from inertiaeffects, seat pounding, etc., which would be troublesome if the checkvalves are made large enough to carry the entire cylinder delivery.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure l is a longitudinal sectional view of a reversible variablestroke pump embodying a preferred form of the present invention.

Figure 2 is an end view of the cylinder block of the pump of Figure l.

Figure 3 is an end view of the valve plate of the pump. of Figure 1.

Figure 4 is a developed view illustrating diagrammatically the action ofthe valve mechamsm.

Referring now to Figure 1, there is illustrated a pump comprising a mainhousing Illl having an. end cover I2. A drive shaft I4 is j'ournalledon. bearings IIiv and has a driving ange I8 at its; inner end. The angeI8 carries a plurality of' sockets 2li which are articulated toconnecting' rods 2-2 having pistons 24 articulated thereto'atA theopposite end. Pivotally mounted in the cas-- ing I0 on hollow trunnions26 is a two-armed swinging yoke 28, arms of which are hollow for'passage of iluid to and from the pintle 26. The yoke carries astationary valve plate 3i) having two arcuate ports 32 and 34 as shownin Figure 3. The valveplate ports communicate respectively withthepassages formed in the yoke 28 and provide the main inlet and outletpassages for the pump. A cylinder block 36 is provided with a pluralityof aXial cylinder bores 38 having indivdual ports 40 adapted to registerwith the valve plate ports alternately as the block rotates in contactwith the valve plate. rIhe cylinder -block 3B isjournalled on a pin 42by means of a bearing 44 while a spring 45 exerts a light'pressureurging the cylinder block into contact with the valve plate 30. Thecylinder block 3.6 is driven in synchronism with the, drive shaft I4 bymeans ofV a Cardan shaft 48 having universal joints 5l! at its oppositeAend.

They structure thus far described is typical of prior art construction,and the present improvementy concerns the. means for valving the fluidto and from the cylinder bores 38. There is provided. in the cylinderblock a plurality of indiv'idual check valves 52v one for each cylinder.The check valves 52 have their inlet side in com- 'shown in dottedlines.

the next adjacent cylinder in a clockwise direc-k tion which would bethe intended direction of rotation of the cylinder barrel shown inFigurel Y 2. The terminus of each passage 56 is also located radiallyinward from the edge of the ports 40.

Referring now to Figure 3, and bearing in mind that clockwise rotationof the cylinder barrel in Figure 2 appears as counterclockwise rotationin Figure 3, the valve ports 32 and 34 have their leading edges locateda considerable angula1` distance from the vertical center line which isthe point of piston dead-center while their trailing edges are locatedapproximately at the normal distance from the Vertical center linethisdistance being substantially one-half the length of each cylinder port43. Each port 32 and 34 also has an inward extension 58 and 60,respectively, which registers with the ends of the passages 56 in turn.

The flat surface between the end of the ports 32 and 34, that is, theportion which effects cut- 'o of each cylinder from both ports, is thusconsiderably longer than the cylinder port 40, and would normally blockeach cylinder for a signicant part of its piston stroke. One of thesecut-olf portions is provided with a depressed cavity or recess 62 of theshape shown. Assuming that the port 32 will be the pressure or outletport for normal forward delivery of the pump, and port 34 the suction orinlet port, the cavity 62 is connected with the port 34 by means of aVposition illustrated, the axis of cylinder block 36 is coincident withthe axis of shaft l4and no re- ;ciprocation ofthe pistons 24 takesplace. The pump is thus in neutralqposition and its iiuic youtput iszero. 1f the yoke 23 be swung away from the observer in Figure 1, theport 34 becomes the inlet port and port 32 the outlet port, and thequantitative delivery of the pump will vary with the angle through whichthe yoke is displaced from neutral position. Likewise, for reversedelivery the yoke may be swung towards the observer in Figure 1 to makethe port 34 the inlet port and port 32 the outlet port, rotation of theshaft at all times being in the direction top to the right in Figure l.

Referring now to Figures 2 and 3, and particularly to Figure 4, thevalve action may be considered. In Figure 4, the parts associated withvalve plate 33 are shown in solid lines, and the parts associated withthe cylinder barrel 36 are The two ends of the iigure represent bottomdead-center of Figure 3 while the mid-point represents top dead-center.It will be noted that in the position shown in Figure 4, cylinder port40 for cylinder No. 1 is at bottom dead-center, and with the yoke 28swung to full forward displacement position, the

4 No. 1 has just cut off from inlet port 34 and the terminus of itscheck valve passage 56 is just starting to connect with the extension 5Bof port 32. Thus, on the first downward travel of its piston, the oilwhich is trapped in the cylinder bore and port at inlet pressure iscompressed at first before the check valve 52 opens. As soon as it iscompressed to a pressure equal to that in the outlet port 32, a slightadditional compression sufcient to overcome the spring behind the checkvalve, opens the same and provides for the initial delivery of all oilfrom said cylinder until port 40 opens to port 32. Since the pistonmovement is substantially simple harmonic motion, the initial travel ofthe piston is small in relation to the angular travel of the cylinderbarrel so that the check valve 52 need not have a large iiuid carryingcapacity. As soon as port 40 establishes connection with port 32, allfurther delivery from the cylinder takes place through port 4l) untilthat port is cut off at the trailing edge of port 32 whichr occurs attop dead-center.

Thereafter, the port 40 is cut olf from communication with port 34 for aconsiderable angular movement of the cylinder block, but is incommunication with therecess B2. During the initial retraction movementof the piston, as for example the piston shown at No. 6 in Figure 4, theoil which was trapped in the cylinder bore and port is initially underfull delivery pressure, and this holds the check valve 64 tightly on itsseat. Retraction of the piston, however, permits this oil to re-expanduntil it has dropped to a pressure slightly below the pressure inv theinlet port 34 at which time check valve 64 opens permitting intake offluid through this path. Upon a further movement of the cylinder barrel,port 40 connects with the main portion of port 34, and the remainingpart of the suction stroke takes place with all oil going through theport 40.

It will thus be seen that the initial connection of each cylinder withboth the inlet and the outlet port is established temporarily through apassage containing a check valve. This provides au automaticcontrol ofthe point at which ow starts, and allows the trapped oil in the cylinderbore and port to be brought up or down in pressure as required toexactly match the pressure in the valve port to which it is to beconnected.

Thus, the actual timing is Varied automatically, depending upon pumpspeed, operating pressure, and piston stroke, as is necessary under thevarious conditions. At the same time, the main flow to or from eachcylinder takes place through wide clear passages imposing littlerestriction.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. In a multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative' reciprocating motion thereof, a main inlet port, amain outlet port. a rotary valve operable in timed relation with thepistons thereof and controlling communication with the main inlet andoutlet ports of the device, individual small discharge passages, one foreach cylinder, and connecting with the main outlet port during only thebeginning of each piston discharging stroke, a check valve in eachpassage, and separate larger passages, one `for I5 each cylinder,connecting with the main outlet port during a later phase of the pistonstroke and also connecting with the main inlet port during the pistonreturn stroke.

2. In a, multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative reciprocating motion thereof, a main inlet port, amain outlet port, a rotary valve carried by the cylinders and operablein timed relation with the pistons thereof and controlling communicationwith the stationary main inlet and outlet ports of the device,individual small discharge passages, one for each cylinder, andconnecting with the main outlet port during only the beginning of eachpiston discharging stroke, a check valve in each passage, and separatelarger passages, one for each cylinder, connecting with the main outletport during a later phase of the piston stroke and also connecting withthe main inlet port during the piston return stroke.

3. In a multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative reciprocating motion thereof, a main inlet port, amain outlet port, a rotary valve operable in timed relation with thepistons thereof and controlling communication with the main inlet andoutlet ports of the device, individual small discharge passages, one foreach cylinder, and connecting with the main outlet port at the-start ofeach piston discharging stroke, a check valve in each passage, separatelarger passages, one for each cylinder, connecting with the main outletport during a later phase of the piston stroke and also connecting withthe main inlet port during the piston return stroke, and a check valveopening out of the main inlet port to each cylinder in turn to establishinitial connection with the main inlet port.

4. In a multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative reciprocating motion thereof, a main inlet port, amain outlet port, a rotary valve operable in timed relation with thepistons thereof and controlling communication with the main high and lowpressure ports of the device, said valving structure having a lengthenedportion at one dead-center position of the pistons at which the normalcommunication of the cylinder is cut off from both high and low pressureports, individual check valves for each cylinder, and auxiliary meansassociated with the high pressure port for establishing communicationwith the high pressure port through each check valve in turn as thecorresponding piston starts away from dead-center.

5. In a multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative reciprocating motion thereof, a main inlet port, amain outlet port, a rotary valve operable in timed relation with thepistons thereof and controlling communication with the main high and lowpressure ports of the device, said valving structure having a lengthenedportion at one dead-center position o the pistons at which the normalcommunication oi the cylinder is cut 01T from both high and low pressureports, individual check valves for each cylinder, and auxiliary meansassociated with the high pressure port for establishing communicationwith the high pressure port through each check valve in turn as thecorresponding piston starts away from dead-center. the valving structurehaving a lengthened portion at the other dead-center position and acheck valve opening out of the main inlet port and eiective to connecteach cylinder in turn to the main inlet as the corresponding pistonstarts .away from dead-center.

6. In a multi-piston and cylinder liquid pressure energy translatingdevice the combination of a plurality of pistons and cylinders, meansfor causing relative reciprocating motion thereof, a main inlet port, a,main outlet port, a rotary valve operable in timed relation with thepistons thereof and controlling communication with the main high and lowpressure ports of the device, said valving structure having a lengthenedcut-off of the cylinders from both high and low pressure ports at atleast one deadcenter position, and individual check valves, one for eachcylinder, for establishing communication of each cylinder with the highpressure port as the corresponding piston starts away from dead-center.

KENNETH R. HERMAN. RALPH L. TWEEDALE.

REFERENCES CITED The following references are of lrecord in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 924,787 Janney June 15, 19091,081,810 Carey Dec. 16, 1913 2,288,768 Zimmermann July 7, 19422,313,407 Vickers Mar. 9, 1943 2,418,123 Joy Apr. 1, 1947 FOREIGNPATENTS Number Country Date 285,468 Germany 1915 442,450 Great BritainFeb. 10, 1936 506,684 Great Britain 1939

